A dual-system mode of a communication terminal refers to that two independent operating systems, including a first system and a second system, can be mounted in a communication terminal such as a cell phone, wherein a user processes important data in the second system, and processes ordinary data in the first system. The second system is different from a private application program, because a private application program is just a safe application program, and the second system adopts system-level partition and isolation with even better safety. The first system and the second system run concurrently, and the user can choose to enter one of these operating systems, so that data is directly stored into the chosen system where the user handles the data. For example, when the user handles certain data in the second system, the data is automatically stored into the second system and cannot be accessed or processed in the first system. But the user might also handle important data in the first system, and if this important data is automatically stored into the open first system alike, then privacy content of the user easily gets leaked.
To sum up, the prior art in practical use apparently has inconveniency and defects, and it is therefore necessary to improve the prior art.